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The Big-Bran Hypothesis

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The Big Bran Hypothesis
Apartment 4B
The Big Bang Theory episode
Season 1, Episode 2
October 1, 2007
Guest star(s)
Craig Duda as
Delivery Man
Episode guide


"The Fuzzy Boots Corollary"
Season guide


Season 2

"The Big Bran Hypothesis" is the second episode of the first season of the American sitcom The Big Bang Theory. This episode first aired on Monday, October 1, 2007.


Sheldon's obsession for cleanliness causes him to break into Penny's extremely untidy apartment in the middle of the night and clean it up. He then gets Leonard in trouble with Penny; however, Penny speaks to Raj who saves the day.

Extended PlotEdit


Moving Penny's entertainment center.

The Big Bran Hypothesis

Leonard and his lightsaber.

Setting their dinner of Thai food, Sheldon gave them a lecture of the use of the fork in Thai history. Penny is in the hallway as they discuss her work at The Cheesecake Factory. She then asks Leonard to sign for a piece of furniture while she is out. They also ask her if they want to join them later for Thai food and a Superman movie marathon. Penny is not sure how many there are, but she does like the one where Superman catches Lois Lane from falling. As Sheldon starts an argument on how that is impossible, Penny sneaks off to work.

It turns out the furniture is bigger than they had expected. The delivery man did not help them to carry it, so Leonard and Sheldon was forced to do it themselves. Since they were not physically strong and they have to do it on the stairs, it was hard for them to do the task. Sheldon only idea involves using a Green Lantern power ring. After having a difficult time, they eventually succeed in getting it up the stairs to her apartment. While there, Sheldon sees that Penny's apartment is a complete mess and insists on tidying up, but Leonard said that he should not do that because it is not their apartment. Penny returns soon after. Penny asks if they had any trouble and Leonard told her no.


First time Penny goes ballistic! Sheldon cleaned her apartment.

Later that night Leonard is awakened by sounds coming from outside of his bedroom. Realizing that the door is open, Leonard goes across the hall with his lightsaber and finds out that Sheldon has used Penny's spare key to enter her apartment to clean. Sheldon couldn't sleep knowing that outside his bedroom was the living room; and outside the living room was the hallway; and immediately adjacent to the hallway was... this. Although Leonard is initially opposed to the idea, he eventually caves in and helps Sheldon clean to get him back.

Leonard get up the next morning and Sheldon tells him that he slept well. Leonard remarks that a well known folk cure for insomnia is to break into your neighbor's apartment and clean. Sheldon asks if that was sarcasm. Penny awakens to find out that her apartment in a well ordered state and screams about those geeky bastards. Penny charges into Sheldon and Leonard's apartment in a fit of rage about coming into her place while she was sleeping. She demands her key back. Sheldon tells Penny that she might want to see a an otolaryngologist about her snoring. "It’s a throat doctor," he explains. Penny then asks Sheldon what kind of doctor would remove a foot from somebody's ass. Leonard holds up a sarcasm sign to let Sheldon know what Penny meant.


Leonard apologizing to Penny.

Later, Penny runs into Rajesh in the hallway and talks to him about being upset over what happened (although he doesn't reply as he has selective mutism). Penny decides to forgive them while Raj was thinking; "Boy, her hair smells nice" and "Maybe my mother was right. Maybe I should marry an Indian girl. We would have the same cultural background and she could sing the same lullabies my mother sang to me". Penny then hugs Raj, much to his surprise. He then turns his pelvis to avoid embarrassing himself. Later, Leonard tries to apologize with several analogies referencing moments in history where errors in judgment resulted in positive outcomes. Penny cuts him off, and then hugs him saying, "We're okay". Later, the guys help Penny put together her media center, but get so focused on the task that they don't hear her when comments that she's hot and is going to take off her clothes. Soon they get completely carried away and go to the garbage dump to find better materials, leaving Penny to do it by herself and would possibly leave the guys completely embarrassed when they see that she's finished the job herself.


  • "A really enjoyable follow up to the pilot. Sheldon’s convictions create a plausible and funny source of conflict for the newly forming group of friends. The writers work really hard here to build a credible world for the characters which feels real and is funny. Long may it continue." - The TV Critic's Review
  • IMDb user reviews


  • Title Reference: The Big Bran is one of Sheldon's high fiber cereal. After cleaning Penny's apartment he feels a sense of accomplishment and opted to consume the Honey Puff cereal (Low Fiber) but after hearing Penny's frustrated yelling he settles for the Big Bran.
  • Chuck Lorre's vanity card.
  • This episode was watched by 8.58 million people with a rating of 3.4 (adults 18-49).
  • Episode transcript.

Costume NotesEdit


Distressed Superman


Rainbow Bolts

Angled striped tee

Angled Striped


Unknown "fans" shirt

Sheldon wears multiple shirts in this episode, starting off with a worn (distressed) light blue shirt with a Superman logo (available at  and When Penny's box arrives, Sheldon is wearing a multi-colored rainbow t-shirt by Aviator Nation/Revolve Clothing (occasionally found at; use search term "rainbow bolts"). The next morning when Penny arrives angry that Sheldon entered her apartment, he can be seen wearing a blue t-shirt with angled green stripes. This shirt was originally available through Urban Outfitters but has been discontinued. By the final scene in Penny's apartment, Sheldon is wearing a white t-shirt with a pattern of multiple fans. Information on this item would be appreciated.




Leonard's APS shirt


Deter 3 Penguins

Leonard starts out wearing a black t-shirt with the molecular structure for caffeine. When Penny's box arrives, Leonard can be seen in a t-shirt from The American Phytopathological Society (a non-profit membership organization dedicated to plant pathology - they make their shirt available to the public, so please support them and buy a couple!). After the blow up with Penny, Leonard sports a black shirt with a wolf howling at the moon. As the guys discuss Penny's entertainment center, he wears a blue shirt with a blue maze pattern.


Bat buckle


Nintendo Controller


Red/Black Vans


Green Lantern buckle

In the opening scene, Howard wears a white alien head pin, Batman cutout belt buckle, and yellow and black Vans shoes. As he dances to X-box, he wears a red alien head pin, red and black Vans shoes, and a Nintendo buckle. In the final scene in Penny's apartment, he has a Green Lantern belt buckle and has gone back to the yellow and black Vans.

Set NotesEdit


The model of the DC-7 on the bookshelves behind the couch has been replaced with a model of the space shuttle Atlantis (it turns up later in Leonard's bedroom). New items on the set include a Spirit of St. Louis radio and a LogiTech iPod Audio Station (model S-2017A ), both found on the shelves next to the front door.


  • Sheldon is wrong about the physics of pushing the furniture up the stairs. This is not just a question of work (energy) but also of power (energy/time). Since he and Leonard cannot produce an unlimited amount of energy per second (say), they may need to push it slowly, contrary to what he asserts. (This is a VERY serious and VERY basic error for a physics PhD!.)
  • As Raj searches for chop sticks, Sheldon educates the gang about chop stick use: they aren't to be used for Thai food, as Thailand has had the fork since the late 19th century; however, they typically don't use the fork to eat, but rather as a method to load food onto a spoon, which is used as a primary eating utensil.
  • First time it's seen that Sheldon is allergic to bees.
  • First time it's seen that Howard is allergic to peanuts.
  • First time it's seen that Leonard has 2,600+ comic books.
  • First time the inside of Penny's apartment is completely seen. In the pilot Penny is seen standing in it through the and the area around the door is seen from inside the apartment.
  • First time it's seen that Sheldon has possible Obsessive-Compulsive disorder and has trouble understanding sarcasm.
  • Sheldon did not knock his now famous three knocks when he went to apologize to Penny.
  • Sheldon states that he has got a masters and two PhD’s.
  • The book that Leonard picks up in Penny's apartment after carrying up her furniture with Sheldon is 'The Secret' by Rhonda Byrne.
  • When putting Penny's furniture together Howard complains over IKEA's pictographic representation-assemble manual and states that these instructions are why Sweden doesn't have a space program. This statement was true when the episode was aired in 2007. It should be noted that Sweden later have got a highly developed space program.
  • First time it's seen that Penny is shown to be a slob and has a temper.
  • Sheldon says, "Yes, but they all involve a green lantern and a power ring." This fact is a reference to DC Comics Green Lantern, a superhero and intergalactic police officer with a power ring that translates his ideas into green energy using the strength of his willpower and is charged by a Green Lantern Power Battery.
  • Leonard states, "Now we've got an inclined plane. The force required to lift is reduced by the sine of the angle of the stairs, call it thirty degrees, so about half." Sheldon corrects him, "Exactly half." Let \angle_{\mathrm{stairs}} \equiv \theta. \mathrm{Then,} \sin{\theta} \approx \sin{30^{\circ}} = 1/2 is what Leonard sought. Actually, it appears Leonard wanted to say \sin{\theta} \approx 1/2 \ (\mathrm{as} \ \theta \approx 30^{\circ}), \ \mathrm{not} \ \sin{30^{\circ}} \approx 1/2, but already interjected, thus, causing this blunder.
  • Leonard wielding a lightsaber as a weapon and flashlight, upon hearing a noise is a hold-over from the Unaired Pilot.
  • Raj's name is revealed to be Rajesh Koothrappali for the first time.
  • The Petre Devos picture by Xavier Allard in Leonard and Sheldon's kitchen appears for the first time. It would remain from this point on.
  • Arguments about Superman and his powers aren't new. Along similar lines, science fiction author Larry Niven did a great piece called Man of Steel, Woman of Kleenex about the science and challenges surrounding sex between Superman and Lois Lane, as well as how Lois could survive a Kryptonian orgasm (the term "mind blowing" would have a whole different connotation if sleeping with the Man of Steel), or a surviving pregnancy with a super-baby inside her. Great food for thought and debate, from his book All the Myriad Ways.
  • Sheldon mentions the Mandelbrot Set of complex numbers. He's referring to a set of complex numbers; one "real", like normal numbers we're all familiar with, plus one "imaginary number", Imaginary numbers are needed because you can't do things like square a real number and get a negative number, or take the square root of a negative number and get a real number...thus i was invented. It is used extensively in complex functional analysis, in electronic and control engineering and in many other fields. Here, it allows the graphing of fractals and establishing magnitudes, rather than dealing with actual values. If you're interested in learning more about the Mandelbrot set, fractals, and chaos theory, try reading James Gleick's classic book Chaos, Making new Science


Leonard: You convinced me. Maybe tonight we should sneak in and shampoo her carpet.
Sheldon: You don't think that crosses the line?
Leonard: Yes! For God's sake, Sheldon, do I have to hold up a sarcasm sign every time I open my mouth?
Sheldon: You have a sarcasm sign?

Raj: Are there any chopsticks?
Sheldon: No need for chopsticks, this is Thai food.
Leonard: Here we go.
Sheldon: Thailand has had the fork since the latter half of 19th century. Interestingly, they don't put the fork in their mouth; they use it to put the food on a spoon which then goes into their mouth.
Leonard: (To Raj) Ask him for a napkin, I dare you.

(While trying to figure out how to get box with furniture to Penny's apartment)
Leonard: We don’t need strength, we’re physicists. We are the intellectual descendants of Archimedes. Give me a fulcrum and a lever and I can move the Earth, it’s just a matter… (starts to move package) I don’t have this... I don’t have this I don’t have this.
(Sheldon catches Leonard and the box)
Sheldon: Archimedes would be so proud.

Sheldon: Ah, gravity, thou art a heartless bitch.

(The morning after Sheldon has cleaned Penny's apartment.)
Sheldon: I'm feeling so good today, I'm going to choose from the lower fiber end of the shelf. Hello, Honey Puffs.
Penny: (from across the hall) SON OF A BITCH!
Leonard: Penny's up.
Leonard: How did she know it was us?
Sheldon: I may have left a suggestive organizational schematic for her bedroom closet.
Leonard: God, this is gonna be bad.
Sheldon: Goodbye, Honey Puffs. Hello, Big Bran.


  • Sheldon's first visit to Penny's apartment.
  • Leonard heard a sound and is defending himself with the FX model of Luke Skywalker's light saber.
  • Sheldon explains Thai food.
  • The Gang.
  • Penny's messy apartment.
  • First time Penny really loses it!
  • Sheldon asks for an explanation of Penny's anger.
  • Sheldon doesn't understand her sarcasm.
  • Give me my key back.
  • Moving the furniture box upstairs.
  • "Helping" Penny.
  • Thank you Raj for listening.
  • Penny asking a favor.
  • Leonard apologizing.
  • Carrying up Penny's new media center.
  • Carrying up Penny's new media center.
  • Leonard.
  • Dancing DDR!
  • She did smell good.
  • Improving Penny's media center.
  • What kind of doctor removes a foot from an ass?
  • Penny stares at Sheldon.
  • First time her Cheesecake factory uniform appears.
  • Chuck Lorre Productions, #184.
  • The gang deciding how best to organize Penny's apartment.

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